There is no experimental evidence that they can perform ATPsynthesis.

In addition to ATP synthesis, prokaryotic cells can use the proton motive force to supply energy for active transport of molecules across the plasma membrane, and to power the motor complex that rotates the bacterial .

A protonmotive force drives ATP synthesis in bacteria.Proc.

Protons consumed per ATP synthesized

From the thermodynamicconsiderations less then 3 protons pro ATP is hardly feasible, for theenergy required for ATP synthesis under physiological conditions isabout 50 kJ mol-1(~520meV), so atphysiological values inthe range of 120-200 mV at least 3 protons should be transferred to getthe energy necessary.

10/4 (because 4 protons per ATP) --> 2.5 ATP.

(2003) (1): 61-70.4) Nice movies at From the early experiments with mitochondria the H+/ATPratio for ATP synthesis was estimated as 3.

ATP Synthase Flashcards | Quizlet

Two protons transferred per ATP synthesised after flash activation of chromatophores from photosynthetic bacteria.FEBS Lett.97:367–372

what part of ATP synthesis catalyzes ATP hydrolysis

A comparison between the phosphate potential and the electrochemical proton gradient showed that the data found are in agreement with a stoichiometry of 2 protons translocated per molecule ATP synthesized.

Hydrolysis and Synthesis of ATP by Membrane-Bound …

The dominant strategy involves a molecule called ATP, which is synthesized from ADP and phosphate through the enzymatic action of a special protein (ATP synthase). Naturally, since this process is essential for the functioning of any organism, ATP synthase has been major research subjects for many years. An analysis of the enzyme structure by Masasuke Yoshida led to a prediction by Paul Boyer that it actually rotates while converting ADP to ATP and storing energy. Rotation is not the only significant aspect, since it was also predicted that the catalysis functions like a motor with two driving units and a common shaft. This view was furthered by J. E. Walker through an X-ray crystallographic analysis. Still, firm evidence was needed. This was recently achieved by Yoshida, who attached a very long (1-3 micrometers) actin filament with a fluorescent marker to the upper motor (10 nanometer diameter) and actually made a video of the rotation.

If we assume that 3 protons are transported per each ATP molecule ..

The catalytic mechanism of ATP synthasemost probably involves rotation of Gamma subunit together with subunitEpsilon and -subunitoligomer relative to the rest of the enzyme. Such rotation wasexperimentally shown for ATP hydrolysis uncoupled to protontranslocation. Moreover, recent experiments revealed, that if Gammasubunit is mechanically forced into rotation, ATP synthesis takes placeeven without proton-translocating FO-portion. It seems most probable that such rotation takes place . However, there is nodirect experimental evidence for such rotary mechanism in the intactenzyme under physiological conditions. The proposed mechanism is the following:

Thermodynamics of proton transport coupled ATP synthesis.

ATP hydrolysisrates is a less clear issue, for the coupled enzyme in small membranevesicles (most commonly used experimental system) quickly builds uprelatively high protonmotive force that acts as a back pressure andstops the hydrolysis.

Thermodynamics of proton transport coupled ATP synthesis…

The motor of c subunits has a 10 fold symmetry. Each subunit releases a proton as it drives a 36 degree movement of the gamma subunit shaft. The sixfold symmetry of the ATP FoF1 synthease is completely separate from this, and every 360 degree rotation, three ATPs are generated. As long as the c motor keeps spinning more ATP is created.

ATP Synthesis Flashcards | Quizlet

An electrochemical gradient of protons, which was artificially imposed across the membranes of Streptococcus cells by manipulation of either the K+ diffusion potential or the transmembrane pH gradient, led to ATP synthesis.

Start studying Lec14: ATP synthase

Through the accumulated investigations, ATP synthase is now being pictured as acting like two motors connected by a common rotary shaft. The energy source is food which supplies hydrogen while discarding carbon as carbon dioxide. The hydrogens are burnt in mitochondria through respiration with pumping out hydrogen ions (protons) from mitochondria. A buildup of protons causes a proton potential difference across a biological membrane; this acts as the power source to rotate the lower motor (F0) of ATP synthase. A connecting shaft causes the upper motor (F1) to rotate While synthesizing ATP. This two-motor-like molecule, which has great likeness to an actual macroscopic motor, can also be run in reverse while changing ATP to ADP and flowing protons in the opposite direction. Some bacteria actually use this capability to transport nutrients.